Technology for mobile electronic devices is improving constantly. Further, key components of mobile electronic devices such as optical imaging lens are updated frequently. As a result, applications of mobile electronic devices are no longer limited to taking pictures or videos. To satisfy consumer demands and perform various optical applications, mobile electronic devices may utilize a telephoto lens to achieve a larger field of view. As the focal length of the mobile electronic device is lengthened, the amplification factor of the optical zoom of the mobile electronic device increases.
However, the focal length of the lens is inversely proportional to an amount of light entering the lens. Further, the effective radius and the volume of the lens are increased when the size of the aperture is increased. Therefore, it may be desirable to increase the focal length to about 8 mm or more than about 8 mm, and to increase the size of the aperture and the amount of light (Fno is less than 2.6) without affecting the lens volume (the effective radius is less than about 2.5 mm).